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Joined 1 year ago
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Cake day: June 29th, 2023

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  • We know something is out there; galaxies are rotating far too quickly for our understanding of gravity to be correct. This is based on the observable matter.

    For the galaxies to be rotating at the speeds we observe, we need approx 5 times the matter we see. So it is not like we have missed 10 - 20% of the matter that interacts with electromagnetic radiation, we would have had to have missed an extra 500%

    As someone else pointed out, MOND is the next most promising candidate, but it has major issues even explaining what we see. Which is why it hasn’t received widespread acceptance.

    I don’t have an answer; I have a few ideas. It maybe that something MOND adjacent is the answer; i.e. on the largest scales spacetime “relaxes” more when there is nothing pulling on it. So near galaxies and clusters spacetime is under more stress, this stress could equate to spacetime curving more on galaxy sized scales. But on the small scales we work on the extra stress will be almost invisible.

    But as for us figuring out what “dark” matter is in your lifetime, unless you are already in your 80’s; I think there is a very good chance. The only thing we know for sure about dark matter, is that it interacts with gravity (spacetime). We are building some pretty epic gravitational wave detectors, bringing the detection threshold lower.






  • As someone with a 5yo.

    Sit on the floor when interacting with them. Literally being on their level can help a lot, that and talk about stuff they are into.

    As someone else mentioned, don’t baby talk to them, unless they have some specific learning disability, a 5yo will know a lot about what they are into (a dinosaur kid will know heaps about dinosaurs)

    My boys all love Lego, build cool stuff, then let them have it, don’t use instructions.


  • Cactus Outdoor.

    I had the original pack now called Vacuole, used it for a long time 10 or so years, lost it one time when moving houses. My boys have one each for school now, I expect them to last for the duration.

    I have two pairs of supertrousers and two pairs of hangdog shorts, all have lasted 6 years so far, daily use in summer / winter for the shorts / trousers.

    The stuff made in the Christchurch factory is epic.






    • RadioLab: so many great episodes on random topics, some absolute gold here.
    • The Subtle Art of Not Giving a Fuck: relatively new, from the author of the best still book of the same name. So far, great!
    • Planet Money: US focused but still really interesting. Economics focused, non political.
    • The Inquiry: BBC deep dive on current affairs.
    • The Forum: BBC deep dive on various topics, some really interesting stuff.
    • Critical Role: its critical role…
    • The Kākā: NZ focused economics and politics.
    • Unexpected Elements: BBC science podcast.
    • The History of Philosophy Without Any Gaps: very deep dive into the history of philosophy.



  • Nuclear Fusion and “net zero emissions” doesn’t really make sense.

    What I think you are trying to say is that fusion is nearing the point where net energy is possible (that is getting more energy out then the amount of energy put in to create the reactions in the first place). Fusion is not practically close yet, but there are tantalizing hints that we are close.

    See this from 2022; the national ignition facility produced more energy that was impacted on the target (2MJ in 3MJ out), but this doesn’t take into account the huge inefficiencies in the laser generators to produce that 2MJ laser pulse.

    There are a bunch of fusion experiments that are hitting massive temperatures (120 - 150MK) which is starting to get into the range where practical fusion could occur, the center of the sun is approx 15MK but also has massive gravity to encourage fusion.

    So fusion is still a decade away at least, but we understand the science much more completely now. We know the problems (well a bunch of them) and it is mostly now a very difficult engineering problem rather a problem of understanding the science.